This invention relates to tree severing apparatus, and more particularly to feller/buncher heads for successively cutting growing trees and accumulating a small bunch in the felling head before placing them in larger bunches on the ground. Feller bunchers in general are discussed in my U.S. Pat. No. 5,697,412. The present invention is an improvement on the feller buncher head described in that patent and the prior art cited therein.
My U.S. Pat. No. 3,875,983 describes the most predominant art of tree accumulation with a harvesting head in North America from the mid 70s to the mid 90s. It can be seen in FIGS. 6 to 11 of that patent that the geometry of the (taker) arms 70 and 75, which first grasp trees and of the (tucker) arms 90 and 91 which then accumulate them, are symmetrical about the centerline of the head. At that time we were only concerned with getting several trees behind the arms and thought that once we had them there they would somehow look after themselves in forming a bundle. There was no concern about how the trees nested amongst each other to form a bundle and the three trees in FIG. 11 of that patent are shown (impossibly) stacked in a center located row. In practice trees do not remain aligned that way and the later trees taken must fall into place amongst those taken first. Often trees crisscross with each other and the operator must abort the cycle without all the available space in the arms being filled with trees. Only a very experienced machine operator can fully load such a head. He does so by skillfully introducing successive trees from one side instead of the center, despite the symmetrical geometry. The usual number of 6 inch diameter trees that are taken with this design of head, hereinafter referred to as xe2x80x9colderxe2x80x9d Prior Art in this application, is three to five, but crisscross often prevents this.
Felling and accumulating heads by other inventors also did not fully attend to the details of getting tree stems to stay neatly aligned in their storage areas. Some like Smith in U.S. Pat. No. 3,805,860 and Tucek in U.S. Pat. No. 3,910,326, as examples, did push the taken trees against a curved backing shape with a single tucker arm, which was a start towards making a good bundle. But because these heads have two symmetrical taker arms, the bundle tends to be pushed away from the backing shape each time another tree is being admitted by the tuckerxe2x80x94an action that often knocks the stems out of alignment. FIG. 4 in the Smith patent illustrates clearly how the lower taker arm 28 has pushed the tree bundle t away from the backing 30b, where it was in the earlier FIG. 3 sequence and where it has to return to after txe2x80x2 is embraced by the tucker 54.
Still others such as Gilbert in U.S. Pat. No. 5,109,900 and Maclennan in U.S. Pat. No. 5,113,919 use a single tucker arm and two symmetrical taker arms that push trees into a large radius backing shape that does even less guiding than the multi-sided U-shape in my older Prior Art. This wide backing shape and the lack of agreement between the takers and the tucker about where the first trees should be stored also results in poor bundle building.
Building a bunch in the center with these symmetrical taker arm heads has two disadvantages. Nesting alignment is poor, because due to torque imparted from bypassing arms being at different elevations, the stack usually falls to one side at its top backing and to the other side at the bottom backing, creating a crisscross mess. And, as a bunch is built up in the middle of the severance area, it prevents the taking of a final large tree. It is preferred to move cut trees at least slightly to one side for accumulation in a V area, where alignment is guided, and where the first trees do not immediately reduce the tree size that can still be cut.
Canadian patent no. 1,103,130 (Hamilton) and U.S. Pat. No. 4,921,024 (Wiemeri) are illustrative of some felling heads that were able to gain extra tree storage capacity by providing a space (a pocket) to one side and rearward of the tree cutting area. A taker arm operating from the side of the head opposite to the pocket swept trees from the severing area into the pocket. There they were accepted by a tucker that operated from the same side of the head as the pocket location. However due to practical geometry limitations, it was not possible for these inventors to make their tucking (accumulating) arms and their taking arms, coming from opposite sides of the pocket, cooperate in building a neat bundle.
Thus in my U.S. Pat. Nos. 5,697,412 and 5,931,210, where it is an objective to store an even larger number of trees, there is provided a more defined corner in a storage pocket and trees are placed there by an arm geometry which operates only from the side opposite the pocket. The taker and tucker arms previously operating from the other side have been omitted because it is not wanted, with each tree taken, to push the trees out of the corner where the pocket-opposing arms have placed them. The working scheme of such geometry is fully explained in those patents. It is the tucker that determines the shape of the bundlexe2x80x94after the taker has gone for another treexe2x80x94and the taker (or takers) should agree with that shape when it returns. Some versions of these devices, hereinafter referred to as xe2x80x9crecentxe2x80x9d Prior Art, accumulate a practical maximum of fifteen 6-inch diameter trees and seldom experience crisscross.
In plantation harvesting logging conditions where trees are small and orderly this improved accumulation ability has led to full acceptance of this recent Prior Art over the older Prior Art. But in natural stands where some trees are very large in diameter and some have already fallen or leaned severely, the newer Prior Art is lacking in some abilities often neededxe2x80x94picking and gathering downed trees and holding large diameter trees briefly when felling. It can be seen in FIG. 3 that when it is necessary to pick up a tree stem that is already lying flat to the ground an older Prior Art head can be placed with one of its open taker arms tips on each side of the stem. As the arms are closed the tree stem can only move on the ground until opposed by the other tip and then it must be scooped up into the accumulation space. In FIG. 5 it is seen that if this is attempted with the newer Prior Art head the single arm tip will sometimes just nudge the stem along the ground and not get under it.
FIG. 4 shows older Prior Art embracing an oversized tree with balanced normal force directions at the arms. FIG. 6 shows the newer Prior Art attempting to hold the same tree stem and the evident lack of balanced forces. For most logging contractors it would be beneficial to use a versatile head that would cut and accumulate small trees at maximum efficiency and then also fell large trees singly when they occur.
Accordingly, it is an object of this invention to provide a tree felling and accumulating head that retains the better accumulation characteristics of the newer Prior Art while regaining the gathering and big-tree holding abilities of the older Prior Art.
It is now recognized from the success of my newer Prior Art that it is good for orderly tree accumulation to have a V backed pocket which is offset to one side of the head and which is loaded by a taker and a tucker operating from the opposite side of the head. Yet it is also recognized that the second taker, which has been discarded because it interfered with good bundle building, is now often missed because of the loss of its gathering and big tree holding actions.
This invention therefore introduces a form of second taker, with action geometry that operates in the tree-getting area but does not ever close down onto the bundle of stems being accumulated. The geometry of the cranks and the link that drive this second taker are designed and built with such proportions that after normal closing action in the gathering and big-tree-holding sweep area any further closing action of this second taker is retarded, and can even reverse slightly, as the first taker is fully stroked.
In the following description, for explanation ease I have mostly referred to this different-action new arm as a xe2x80x9csecond takerxe2x80x9d because its location and external appearance are like those of a taker. In its practical use however, to avoid adding to the confusion that exists in nomenclature of felling head arms, and since it does not take the trees all the way into the accumulation area it is preferred to call it a xe2x80x9cpickerxe2x80x9dxe2x80x94a better description of its work.
In the following illustrations and detailed descriptions it is shown that the sweep area of this picker is such that when the taker is in the tree gathering and big tree holding positions, the taker gets the same assistance from the picker as it would from a prior art opposing taker. It is also shown that unlike an ordinary taker the picker does not encroach into the tree storage area that is used by the first taker and the tucker for orderly bundle building.